Huan Wen vs Yeon Gaesomun

Huan Wen led a campaign to conquer the Cheng Han state in Sichuan. He defeated the Cheng Han army and captured its capital Chengdu, annexing the region into the Jin Dynasty and expanding Jin territory.

Huan Wen launched a series of northern expeditions against the Former Qin and other states. He achieved initial victories but failed to hold territory, ultimately retreating due to lack of supplies and political opposition at court.

Huan Wen deposed Emperor Fei of Jin and installed Emperor Jianwen, a puppet ruler. He sought to usurp the throne but died in 373 before completing his plans, leaving his son Huan Xuan to later attempt the same.

Yeon Gaesomun led a military coup, killing King Yeongnyu and hundreds of nobles. He installed King Bojang as a puppet ruler and assumed the position of Dae Mangniji (Supreme Commander), establishing a military dictatorship over Goguryeo.

Yeon Gaesomun refused to submit to Tang Chinese demands for tribute and recognition, asserting Goguryeo's sovereignty. His aggressive stance led to multiple Tang invasions and a prolonged war that drained both empires.

Yeon Gaesomun led the defense of Ansi Fortress against a massive Tang Chinese invasion led by Emperor Taizong. The Goguryeo forces held out for months, inflicting heavy casualties and forcing the Tang army to retreat, preserving Goguryeo's independence.

Yeon Gaesomun died, leading to a power struggle among his sons. This internal division weakened Goguryeo, allowing the Tang-Silla alliance to conquer the kingdom in 668, ending its 700-year history.